The present invention relates generally to electrical machines of the type having a rotor and field windings, including end windings about a rotor body, and particularly relates to flattened end windings across the width of a pole in conjunction with a cap affording cooling medium flow ventilation radially outwardly of the end windings.
In electrical machines, for example, generators, there is provided a rotor body having field windings which generally form arcs at opposite ends of the rotor body and are called end windings. The end windings typically extend generally axially from the rotor body and cross over supports or spindles in a circumferential direction adjacent opposite ends of the body for return in an axial direction into and along the rotor body. In a typical generator construction, the windings are located in slots in the rotor body and wedges secure the windings in the slots. The end windings are typically separated from one another by spacer blocks. More recent generators include a rotor body having defined pole regions with pole faces and parallel sides, together with prefabricated winding modules extending along the parallel sides with the prefabricated end windings extending between end faces of the rotor body. In both types of generator constructions, the end windings extend arcuately about the supports or spindles at opposite ends of the rotor body. A retaining or enclosure ring conventionally overlies the end windings forming essentially a cylindrical ring about the end windings.
It will be appreciated that the field windings, including the end windings, are cooled by passing a cooling medium through or along the rotor windings. Typically, grooved passages are formed in the field windings internal to the copper and channel the cooling medium so that it can be discharged radially outwardly into the gap between the rotor and stator and axially inwardly of the end retaining or enclosure rings. Thus, the end retaining or enclosure rings serve as obstructions to the discharge of the cooling medium channels through the rotor end windings.